Python 3 Tutorial - Sets
In this video tutorial you will learn what Python sets are and what they can do for you.
The demonstrations include intersection, union and difference set operations - both using member functions and with operators. Finally a brief example of how sets can positively affect the performance of your programs is shown.
The following source code was used in this video tutorial:
s1 = {1, 2, 9, 3, 1, 3, 7, 9, 3, 1, 3, 2}
s2 = {5, 8, 4, 3, 7, 8}
intersection = s1.intersection(s2)
s1 & s2 # binary and operator
union = s1.union(s2)
s1 | s2 # binary or operator
s1.difference(s2)
s1 - s2
example of how sets can help improve your program's performance
by removing a nested for loop (O(n*m))
query1 = list(range(1, 100000, 2)) # 1, 3, 5, ...
query2 = list(range(1, 100000, 3)) # 1, 4, 7, ...
nested loop
records = []
for record in query1:
if record in query2:
records.append(record)
and now with sets
queryset1 = set(query1)
queryset2 = set(query2)
records = list(queryset1.intersection(queryset2))
--
This screencast was recorded using the kate editor, ipython3 shell and Kazam screencaster on Kubuntu 14.04.
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